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The Minnesota Department of Agriculture (MDA) and partner organizations are proposing to manage spongy moth (Lymantria dispar) infestations this summer in nine counties across eastern Minnesota.

Spongy moths are ranked among America’s most destructive tree pests and can cause significant environmental and economic impacts. Spongy moth is a leaf-eating insect that has caused millions of dollars in damage to forests across the United States. This pest is found in most of Wisconsin and is now establishing itself in northeastern and southeastern Minnesota.

The MDA monitors for spongy moth each year, surveying for emerging infestations. When an infestation is found, the department conducts aerial management and targets the infestation before it can spread. The number of spongy moths detected in Minnesota in recent years has increased, and populations continue to push westward.

Forty-three treatment areas totaling approximately 115,000 acres are proposed in Aitkin, Anoka, Carlton, Fillmore, Houston, Itasca, Pine, St. Louis, and Winona counties. The areas will be managed with either: Bacillus thuringiensis var. kurstaki (Btk): a biological insecticide that is organically certified for use on food crops, or mating disruption, a substance containing pheromones specific to spongy moths that confuse the male moths and prevent mating. Residents can view an interactive map on the MDA website to determine if they are located within any of the proposed management areas. 

Management will be conducted from May through July, depending on insect development and weather.

The MDA has successfully treated dozens of spongy moth infestations across eastern Minnesota. These successful treatments help postpone the full-scale invasion of spongy moth. They also save local communities and homeowners money and protect the health of the state’s urban and natural forests.

Residents in proposed treatment areas and the public are invited to attend an informational meeting to learn more about the insect and the treatment methods.

To register for virtual meetings, visit the MDA website.

Residents in proposed management areas will also be receiving a postcard with more information. Citizens can also find info on spongy moth management, sign-up for text or email notifications, and see proposed management area maps on the MDA website.

Comments on any of the proposed management activities are being accepted through April 15, 2025. Comments should be submitted in writing via mail or email to:

Kimberly Thielen Cremers
Minnesota Department of Agriculture
625 Robert Street North
St. Paul, MN 55155
Kimberly.TCremers@state.mn.us

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Media Contact
Brittany Raveill, MDA Communications
651-201-6131
Brittany.Raveill@state.mn.us